1. Field of the Invention
The present invention relates to the solvent-induced crystallization of normally solvent-resistant amorphous organic polymers using specific high boiling organic solvents. More specifically, the invention pertains to the solvent-induced crystallization of amorphous poly(etheretherketone) (PEEK)-type polymers, amorphous polymers having similar structures to PEEK, poly-(phenylene sulfide) (PPS) or physical mixtures of these amorphous polymers. Because these polymers are difficult to fabricate and usually require very high processing temperatures, the solvent-induced crystallization of the present invention is very useful because it proceeds at relatively lower temperatures, in some cases more than 100.degree. C. lower than those used in normal solvent fabrication.
2. Description of the Related Art
B. J. MacNulty in the Journal of Materials Science, Vol. 8, pp. 1495-1504, published in 1973, discusses the effect of solvents and mixed solvents on the formation of crystalline entities in polymers having phenylene groups in the main chain. The polymers include, poly(carbonate), poly(sulfone), poly(phenylene oxide), and phenoxy resin. The solvents include chloroform, methylene chloride, acetone, benzene, xylene, and carbon tetrachloride.
W. Koslowski, et al., in Polimery (Warsaw), Vol. 19, No. 10, pp. 483-487, published in 1974 disclose that amorphous nylon 6 is crystallized by exposure to various hydrophilic liquids or water vapor. [See Chem. Abstracts, Vol. 82, 171569q (1975)].
A. B. Desai, et al., in the Journal of Polymer Science, Polymer Symposium, Vol. 46, pp. 291-319, (1974), disclose that poly(ethylene terephthalate) is crystallized in the presence various organic solvents.
N. Overbergh et al., in Polymer, Vol 16, pp. 703-708, published in 1975 disclose the crystallization of isotactic polystyrene induced by contact with low molecular weight organic compound vapor, such as dichloromethane and acetone.
V. Vittoria et al., in Macromolecules, Vol. 19, pp. 1975-79, published in 1986 disclose the solvent-induced crystallization of quenched isotactic polypropylene fibers in a number of low molecular weight organic solvents including n-hexane, octane, cyclohexane, carbon tetrachloride, toluene, benzene, chloroform, chlorobenzene and dichloromethane.
N. J. Tyrer et al., in Macromolecules, Vol. 85, p. 511-518, published in 1985, and also in Vol. 84, pp. 2296-2303, published in 1984, disclose the solvent-induced vapor crystallization of isotactic polystyrene using hexahydroindan and cyclooctane.
H. A. Smith in U.S. Pat. No. 4,118,363 discloses the solution of PPS, as a crystalline polymer having a solubility parameter of between 7 and 12.5, using an alkyl or halogen substituted diphenyl ether.
The general chemistry of aromatic polyethers is described by D. M. White and G. D. Copper, in Kirk-Othmer: Encyclopedia of Chemical Technology, 3rd ed., Vol 18 pp. 594-615 in 1982, which is incorporated herein by reference.
The general chemistry of the polymer (PPS) is described in H. W. Hill, Jr. and D. G. Brady in "Poly(phenylene sulfide)" published in Kirk-Othermer: Encyclopedia of Chemical Technology, 3rd ed. Vol. 18, pp. 793-814, in 1982, which is incorporated herein by reference.
None of these references individually or collectively teach or suggest the present invention of solvent-induced crystallization of normally solvent-resistant polymers, such as PEEK or PPS.
Amorphous PEEK or PPS have not heretofore been subjected to solvent-based crystallization. Because of their high solvent resistance, it is not possible to predict a priori whether or not solvent-induced crystallization will proceed or which solvents are useful for solvent-induced crystallization.